Spectro-temporal mapping of left bundle branch block

Selected Abstracts From tla;eEighteenth International Congress on 23lectrocardiology

Postexercise Changes oHlw QTc Interval Patients With #s&nt Myocardial Infarction

Spectra-temporal Mapping of Left Bundle Branch Block H. Decoster, J. Snoeck, M. Verherstraeten, L. Francque, M. Berkhof, Department of Cardiology, University Hospital Antwerp, Antwerp, Belgium

Mario Garcia-Alves, M. Carvalho, A.P. Lacerda, 1. Dionisio, F. Monteiro, G. Cantinho, E. MacieiraCoelho, F. de Padua, St. Mary University Hospital, Center of Cardiology INIC (Professor F. Padua, LA 3), and Nuclear Medicine, Lisbon, Portugal.

Spectra-temporal mapping (STM) is the use of Fourier analysis in a time-sliced ECG QRS-complex. The result is a 3-dimensional display of the power, frequency, and time information within the QRS complex. To determine the clinical relevance of this new technique, we compared the results of STM to those of the well-known time domain analysis. The major disadvantage of time domain analysis is the low sensitivity and specificity caused by an inability to detect micropotentials (which are the electrocardiographic reflection of electrical microreentry circuits in the myocardium and the origin of ventricle tachycardia) hidden in the QRS complex itself:Only micropotentials localized in time at the end of the depolarization of the ventricle are detected .byn’me domain analysis and are called late potentials. We studied 35 VVI paced patients ‘with an old myocardial infarction or coronary artery disease. Signal averaging using the time .domain analysis technique was performed twice in each patient; the first time only to nonpaced QRS complexes and the second time only to paced complexes. Hence, each patient was used as his own control. Thereafter, STM was performed only on paced, large QRS deflections. Signal averaging using time domain analysis was not able to detect late potentials in patients with left bundle branch block QRS morphology due to right ventricle pacing. However, late potentials were present in the same patients when signal averaging was performed using the same technique in nonpaced small QRS morphology. Spectra-temporal mapping performed during right ventricle pacing with large QRS complexes was again able to detect the presence of micropotentials. STM is a promising new technique. It improves the sensitivity and specificity for

, A lack of a QTc ratio decrease at maximal exercise is considered an index of exercise-induced ischemia. Fifty-two ,_,patients were studied within 3 months after thafirst myocardial infarction in order to evaluate the QTc changes with exercise in assessing the presence of remaining ischemic myocardium. The patients were submitted to exercise testing, coronary angiographies, and thallium 201. Of the 52 patients, 23 showed l-vessel disease and 29 showed 2 or 3 vessel disease. Vessels were classified as patent or occluded. Among the 23 patients with l-vessel disease the main lesion was patent in 11 and occluded in 12; 5 of these 12 patients presented with well developed collaterals while the other 7 showed no collaterals. Exercise “‘Tl showed in patients with 2/ 3 vessel disease fixed and reversible perfusion defects in segments related to or remote to the infarct area. Patients with 1 patent vessel disease or 1 occluded vessel disease with collaterals, fixed, and reversible perfusion defects were present in segments related to the infarct area. Patients with 1 occluded vessel disease without collaterals revealed fixed perfusion defects. A lack of the QTc ratio decrease at maximal exercise was seen in all patients except in those with 1 occluded vessel disease without collaterals. Thus QTc variations with exercise in postmyocardial patients are of value in denouncing the presence of remaining ischemic myocardium.

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Journal of Electrocardiology

Vol. 25 No. 3 July 1992

the detection of micropotentials by taking into account the micropotentials hidden in the QRS complex.

Correlations Between Unexpected VCG Changes and the LV Diastolic Function in Type I Diabetes Mellltus G. Gotti, E. Barducci, L. Borgioni, G. Cattarini, R. Magris, G. Mastrobuoni, P. Moratti, G. Zilio, M. Palmieri, CCU and Cardiological Service, General Hospital, Monfalcone, Italy With the purpose of recognizing the early markers of the diabetic cardiomyopathy (DC), 50 normotensive insulin-dependent diabetes mellitus patients (2 1 men, 29 women), aged 20-75, free of cardiac symptoms were studied without knowledge of their clinical and metabolic data. The Frank-VCG loops were examined for bites, ischemia, or LVH. A 2-dimensional ECHO was then performed, the mitral flow investigated, and the Doppler derived E/A wave velocity ratio obtained. Lastly, the glycosylated hemoglobin (HBnlc) and the ratio of the age at onset of diabetes mellitus and the actual age of the patients (DA/PA) were given by the diabetic outpatients clinic. A group of 20 normal subjects matched for age and sex served as controls. According to the VCG findings two groups were recognized: group I-normal VCG, 30 patients (60%), mean age 39.03 (2074 years); 6 (20%) with A/E ratio, mean DA/PA = 0.43, mean HB*,, = 7.38; group II-VCG abnormalities, 20 (40%), mean age 55.45 (31-75 years); at the VCG:bites in 9 (45%), necroses in 2 (lo%), ischemia in 4 (20%), LVH in 7 (35%), IVC defects in 6 (30%). The 2-dimensional ECHO was abnormal in all (100%) cases: A/E ratio in 17 (85%), LVH in 11 (55%), a calcifrc mitral annulus in 5 (25%). Of these:mean DA/PA = 0.52 and the mean HB*,, = 7.81. Clinical findings differentiating group II from group I are as follows: no complications in 3 (25%) vs 14 (46.6%); retinopathy in 12 (60%) vs 10 (33.3%); microaneurysms in 2 (10%) vs 2 (6.6%); neuropathy in 8 (40%) vs 6 (20%); nephropathy in 7 (35) vs 3 (10%); and arteriopathy in 9 (45%) vs 4 (13.3%). VCG bites and IVC defects correlated with the Doppler derived E/A ratio to detect subclinical myocardial abnormalities (34% in insulin-dependent diabetes mellitus patients vs 15% in normal subjects). The correlation is mostly evident in presence of diabetes mellitus noncardiac complications (r = 0.6) or when the HB*,, values reveal a poor m.etabolic control of DM (r = 0.46).

Determination of Infarct Size by QRST Iso-Integral Maps in Dogs Yoshio Ichihara, Makoto Hirai, Yasushi Tomita, Masayoshi Adachi, Akira Suzuki, Hiroshi Hayashi, Nagoya University, Nagoya, Japan In order to determine the size of myocardial infarction (MI), indexes were calculated from the QRST iso-integral map (IQRSTmap) and compared with anatomical infarct size in eight canine hearts. Myocardial infarction was produced by embolization of the left anterior descending artery with glass beads under pentobarbital anesthesia. One week after the production of infarction, body surface ECGs were recorded to construct IoRsT maps with an 87-lead system during RA pacing as a normal conduction model, RA + RV simultaneous pacing as a left bundle branch block model, and sequential RA + RV pacing with an appropriate AV interval as the WolffParkinson-White syndrome model. The QRST indexes were calculated from these IQRSTmaps by summing up QRST integral values over the whole leads in each model. After the experiment, the hearts were excised, and cut along the AV groove into 1 cm slices. The MI size was determined in percent by planimetry of these slices. QRST indexes were inversely correlated with the MI size not only in the normal conduction model (r = -0.89, p < O.Ol), but also in the setting of left bundle branch block (r = -0.73 p < 0.05), and Wolff-Parkinson-White syndrome (r = -0.83, p < 0.01). In conclusion, MI size can be determined using the IoRsT map in a noninvasive way. This diagnosis is preserved in spite of altered activation sequences.

A Comparison of Atrial Volume Between Patients With Atria1 Fibrillation and Sinus Rhythm Fumitake Inomata, Shonan Kamakura Hospital, Kamakura, Japan It was difficult to measure the right atria1 volume (RAV) correctly and noninvasively before the introduction of ultrafast computed tomography (UFCT). RAV was measured in patients with chronic atria1 fibrillation using UFCT in order to test the hypothesis that patients with AF have a larger RAV than those with sinus rhythm. Eight slices of ECG-triggered diastolic left and right atria1 silhouettes were taken with UFCT during the